Abstract Generation of human pluripotent stem cells upon reprogramming of patient-specific somatic cells and subsequent differentiation of the stem cells into more specialized cell types opened new exciting opportunities for human regenerative medicine. Direct reprogramming of fibroblasts to various cell types including neural cells and cardiomyocytes using different sets of bioactive factors was successfully demonstrated for mouse and human cells. However, reprogramming in human cells and adult fibroblasts remains inefficient, and further efforts are needed. While the precise molecular mechanisms of direct reprogramming to mouse and human cardiomyocytes are largely unknown, these studies commonly use viral vectors harboring different cardiac reprogramming factors that integrate into the host cell genome leading to constitutive expression of these cardiac-specific transcription factors. A major drawback of this approach is that viral DNA randomly integrates into the cell genome and may alter the normal gene expression pattern or trigger abnormal oncogene expression leading to cancer and/or other detrimental consequences. Our collaborators at Stemgenics have developed an innovative patent-protected technology using non-integrating functionalized nanoparticles to reprogram mature cells into autologous pluripotent stem cells with ~15% reprogramming efficiency and intact genome. The important aspect of the Stemgenics reprogramming nanotechnology is the absence of any genome integrating elements in the reprogramming system, thus the resulting cells preserve their native intact genome. This technology combined with direct reprogramming of human fibroblasts to functional cardiomyocytes presents unique opportunities for generation of personalized functional cardiomyocytes for patients with cardiomyopathy or heart failure diseases. In this SBIR Phase I proposal, we will 1) generate non-integrating biocompatible nanoparticles functionalized with covalently linked cardiac-specific reprogramming factors, 2) optimize direct fibroblast-to-cardiomyocyte reprogramming efficiency, and 3) characterize functional properties of the resultant human cardiomyocytes. The outcome of our proposal will permit further, more comprehensive Phase II studies for evaluation of directly reprogrammed iCM in vivo by direct reprogramming of fibrotic scars in animal models of heart injury, and will provide invaluable novel tools for efficacy evaluation of different therapeutic drugs directly on patient- specific fibroblast-derived cardiomyocytes with intact genome.